1. Field of the Invention
The present invention relates to a method for manufacturing semiconductor devices which are assembled with the use of, for example, leadframes.
2. Description of the Related Art
FIG. 1 is a flow chart showing a conventional type of method for manufacturing semiconductor devices, FIG. 2 is a schematic perspective view showing a semiconductor device which is assembled by the conventional manufacturing method, FIGS. 3(a) to 3(f) are schematic views which serve to illustrate the process sequence of the conventional manufacturing method, and FIG. 4 is a schematic view showing the manner in which a semiconductor device manufactured by the conventional manufacturing method is subjected to a performance test.
The conventional method for manufacturing semiconductor devices will now be described with reference to FIGS. 1 to 4.
First, as shown in FIG. 3(a), a plurality of semiconductor chips 2 are formed on a semiconductor wafer 1. Then, a sheet 3 is adhesively bonded to the back of the semiconductor wafer 1, and a dicing apparatus (not shown) is used to form grooves 1a in the side of the semiconductor wafer 1 which is opposite to the sheet 3 for the purpose of separating the wafer 1 into the individual semiconductor chips 2 (FIG. 3(b)). After wafer separation, each of the semiconductor chips 2 is bonded to a leadframe 4 by an adhesive 5 (FIG. 3(c)). In this step, a die-bonding apparatus (not shown) is used to perform registration, adhesion, etc. of each of the semiconductor chips 2 and the leadframe 4. Subsequently, a wire-bonding apparatus (not shown) is used to connect each electrode (not shown) of the semiconductor chip 2 to a corresponding inner lead 4a of the leadframe 4 through a metal wire 6 (FIG. 3(d)). The wire-bonded leadframe 4 is molded with a resin by means of a packaging apparatus (not shown), and the resin is formed into a plastic package 7 (FIG. 3(e)). Then, a plating apparatus (not shown) is used to apply a coat of external solder plating 8 to each outer lead 4b of the leadframe 4 (FIG. 3(f)). In this fashion, a plurality of semiconductor chips 2 mounted on the leadframe 4 are packaged by the respective plastic packages 7, and each of the plastic packages 7 is separated from the leadframe 4. Finally, the outer leads 4b of each plastic package 7 are formed into a predetermined configuration and semiconductor devices of the type shown in FIG. 2 are thus assembled.
Each semiconductor device thus assembled is, as shown in FIG. 4, connected to a testing apparatus 9 through a connecting member 9a and is subjected to a performance test. After completion of the test, the semiconductor device is supplied as a product.
The above-described conventional method for manufacturing semiconductor devices, however, leaves the following problems to be solved. First, the arrangements of the physical distributions between respective process steps are complicated and, since the performance of semiconductor devices depends upon the reliability and quality of the equipment used in each process step, as the number of manufacturing devices are increased, high-reliability semiconductor devices become difficult to obtain. Second, since the number of process step is large, a large number of products in process are present between respective process steps and, in addition, since semiconductor devices must be sequentially manufactured in accordance with the order of the process steps after die bonding, the total time period required to manufacture each semiconductor device becomes longer.